A casting mold for spheroidal graphite cast iron

Abstract

The application belongs to the technical field of casting, and particularly relates to a casting mold for nodular cast iron, which comprises a mold base, a mold, an upper mold and a cooling mechanism; the mold base is detachably connected with the mold inside; the mold is internally provided with a casting cavity penetrating through the thickness of the mold, and the inside of the mold base around the mold is provided with the cooling mechanism; the upper part of the mold base is detachably connected with the upper mold, and the bottom of the upper mold is a plane; wherein the mold base comprises a base and a mounting base on the upper part of the base; the upper part of the mounting base is concave downward to form a cavity matched with the mold, and the cavity is detachably connected with the mold inside; the inside of the base is provided with an ejection mechanism, and the top plate of the ejection mechanism penetrates through the upper part of the base and corresponds to the casting cavity, and is used for ejecting the solidified casting from the casting cavity. The application reduces the manufacturing cost of the mold, reduces the replacement time and improves the casting efficiency.

Description

Technical Field

[0001] This invention belongs to the field of casting technology, and in particular relates to a casting mold for ductile iron. Background Technology

[0002] Ductile iron, with its high strength, good toughness, and excellent wear resistance, is widely used in machinery manufacturing, auto parts, hardware, and many other fields. Casting is primarily achieved through sand casting and metal mold casting processes. The casting mold is the core equipment determining the quality and production efficiency of ductile iron castings. Currently, traditional ductile iron casting molds typically employ a separate upper and lower mold structure, with each mold having its corresponding half-cavity machined. After mold assembly, a complete casting cavity is formed. However, different shapes and specifications of castings require separate design and manufacturing of complete upper and lower molds, resulting in significant mold investment. Changeovers require complete disassembly and assembly of the upper and lower molds, which is time-consuming. Furthermore, because the upper and lower molds are machined separately, misalignment is prone to occur during mold assembly, leading to a large amount of flash at the parting surface of the casting. This results in a large amount of subsequent grinding work and affects the dimensional accuracy of the casting. Summary of the Invention

[0003] The purpose of this invention is to provide a casting mold for ductile iron to solve the technical problems mentioned in the background art.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A casting mold for ductile iron includes: a mold base, a mold, an upper mold, and a cooling mechanism; the mold base is detachably connected to the mold, the mold has a casting cavity extending through its thickness, and the cooling mechanism is located inside the mold base surrounding the mold; the upper part of the mold base is detachably connected to the upper mold, and the bottom of the upper mold is a plane. The mold base includes a base and a mounting seat located on the upper part of the base; the upper part of the mounting seat is recessed downward to form a cavity adapted to the mold, and the mold is detachably connected to the inside of the cavity; the base is provided with an ejection mechanism, and the top plate of the ejection mechanism passes through the upper part of the base and corresponds to the casting cavity, for ejecting the solidified casting from the casting cavity; The mold base has an internal heat insulation layer, which is located outside the cooling mechanism and below the ejection mechanism.

[0005] As a further improvement of the present invention, the top of the upper mold is provided with a pouring cup, and the interior is provided with a sprue, a slag collection bag and an inner gate connected in sequence. The upper part of the gating system is connected to the pouring cup, and the middle part is provided with the slag collection bag. The diameter of the slag collection bag is larger than the diameter of the gating system, and the slag collection bag is provided with a slag-blocking mesh inside. The lower part of the gating system is provided with the ingate, and the ingate is connected to the casting cavity.

[0006] As a further improvement of the present invention, the bottom corner of the upper mold is recessed upward to form a guide groove, and the guide groove is in the shape of a frustum that is narrower at the top and wider at the bottom; the upper corner of the mounting base is provided with a guide post that is adapted to the guide groove.

[0007] As a further improvement of the present invention, the mold has downwardly extending guide bars on two opposite side walls, and the bottom of the guide bars has insert rods; The inner wall of the mounting base is provided with two guide grooves, and the guide grooves are dovetail grooves. The guide grooves and the guide bars slide in a one-to-one fit. The bottom of the guide grooves is provided with slots that are adapted to the plug rods.

[0008] As a further improvement of the present invention, a limiting hole is provided at the inner bottom corner of the mounting base, and a limiting rod adapted to the limiting hole is provided at the bottom of the mold.

[0009] As a further improvement of the present invention, the cooling mechanism includes an inlet channel, a cooling channel, and a return port; the inlet channel is disposed inside the base, one end of which passes through the side wall of the base, and the other end is connected to the bottom inlet of the cooling channel; the cooling channel is spirally disposed inside the mounting base, and a small turbulence flow platform is provided inside it, with the upper outlet connected to the return port, and the return port passes through the side wall of the mounting base.

[0010] As a further improvement of the present invention, the ejection mechanism includes a cylinder and a top plate, the cylinder is installed in the storage cavity inside the base, and its piston rod extends upward and is fixedly connected to the top plate; The cylinder's inlet and outlet pipes pass through the side wall of the base.

[0011] As a further improvement of the present invention, the upper part of the base is provided with upwardly protruding slag-blocking strips, and the slag-blocking strips are provided with openings.

[0012] As a further improvement of the present invention, the bottom of the mold base is provided with a heat insulation plate and several through holes around it for fixing and installing the mold base.

[0013] As a further improvement of the present invention, the base and the mounting seat are integrally formed.

[0014] The beneficial effects of adopting the above technical solution are as follows: This invention features a detachable connection between the mold and the mold base; the bottom of the upper mold is flat, eliminating the need for machining complex cavities. When producing castings of different specifications, only the mold needs to be replaced, while the mold base and upper mold are reusable. There is no need to re-machine or replace the main structure of the upper mold and mold base. Compared to the traditional method of replacing the entire upper and lower mold sets, this reduces mold manufacturing costs, shortens changeover time, and improves casting efficiency. Furthermore, the flat bottom of the upper mold allows it to directly contact the upper surface of the mold during mold closing, eliminating the misalignment issues caused by separately machining half-cavities in the traditional upper and lower molds. This reduces misalignment and flash at the parting line of the casting, decreases subsequent grinding work, and improves the dimensional accuracy of the casting. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a main sectional view of the present invention; Figure 3 This is a side sectional view of the present invention; Figure 4 This is a schematic diagram of the upper mold and mold base of the present invention; Figure 5 This is a schematic diagram of the mold of the present invention; Figure 6 This is a schematic diagram of the mold base of the present invention; The markings in the diagram are as follows: 1 Mold base, 1-1 Base, 1-2 Mounting seat, 1-3 Cavity, 2 Mold, 3 Upper mold, 4 Casting cavity, 5 Top plate, 6 Pour cup, 7 Sprue, 8 Slag collection bag, 9 Ingate, 10 Guide groove, 11 Guide post, 12 Guide bar, 13 Insert rod, 14 Guide groove, 15 Slot, 16 Limiting hole, 17 Limiting rod, 18 Liquid inlet channel, 19 Cooling channel, 20 Liquid return port, 21 Cylinder, 22 Storage cavity, 23 Slag baffle, 24 Opening, 25 Through hole, 26 Exhaust port, 27 Insulation layer, 28 Baffle platform. Detailed Implementation

[0016] To better understand the purpose, structure, and function of this invention, the invention will be clearly and completely described below with reference to the accompanying drawings.

[0017] like Figures 1-6The diagram illustrates a casting mold for ductile iron, comprising a mold base 1, a die 2, an upper mold 3, and a cooling mechanism. The mold base 1 serves as the main support for the entire mold, and the die 2 is detachably mounted inside it. The die 2 has a through-cavity 4 extending through its thickness, the shape of which matches the outer contour of the ductile iron part to be formed. The cooling mechanism, located within the mold base surrounding the die, is used for forced cooling of the poured molten iron. The upper part of the mold base 1 is detachably connected to the upper mold 3, whose bottom is flat, greatly simplifying the manufacturing process of the upper mold.

[0018] In this embodiment, the mold base 1 includes a base 1-1 and a mounting seat 1-2 located on the upper part of the base 1-1. Preferably, the base 1-1 and the mounting seat 1-2 are integrally cast, resulting in good overall rigidity and avoiding loosening or sealing problems that may occur with separate connections. The upper part of the mounting seat 1-2 is recessed downward to form a cavity 1-3 that matches the shape of the mold 2, and the mold 2 is detachably installed in the cavity 1-3. An ejection mechanism is provided inside the base 1-1. The top plate 5 of the ejection mechanism passes through the upper part of the base 1-1 and corresponds to the casting cavity 4, used to eject the solidified casting from the cavity 4. The ejection mechanism of the present invention does not adopt a traditional ejector rod structure. There is no need to open an ejector rod through hole at the bottom of the mold 2. The upper surface of the top plate 5 is flat, and its size and shape match the size and shape of the bottom of the casting. After the casting solidifies, the top plate 5 moves upward, and its upper surface directly contacts the bottom surface of the casting, lifting the casting out of the mold 2 as a whole. Because the contact area between the top plate 5 and the bottom surface of the casting is large, the ejection force is evenly distributed, and no local indentations or marks are produced on the bottom surface of the casting, thus ensuring the flatness of the bottom surface of the casting.

[0019] In addition, the mold base 1 is provided with a heat insulation layer 27. The heat insulation layer 27 is located outside the cooling mechanism and below the ejection mechanism. The heat insulation layer 27 is integrally formed by laying aluminum silicate high-temperature heat insulation cotton, with a thickness of 10mm. It can withstand the high temperature of 1280~1380℃ for long-term casting of ductile iron, and is suitable for the continuous high-temperature casting conditions of this mold. The heat insulation layer 27 forms a ring-shaped heat insulation barrier outside the cooling mechanism, which can prevent the low temperature coolant in the cooling mechanism from directly exchanging large-area heat with the outer wall of the mold base and the high temperature metal outside the cavity. This avoids the thermal stress caused by the sudden cooling of the outer wall of the mold and prevents cracking and deformation of the mold body due to long-term alternating hot and cold temperatures.

[0020] To achieve rapid and accurate positioning and convenient replacement, this invention incorporates multiple guiding and positioning structures. For example... Figure 4As shown, the bottom corner of the upper mold 3 is recessed upwards to form a guide groove 10. The guide groove 10 is a frustum-shaped cavity, narrow at the top and wide at the bottom, i.e., a tapered hole. A guide post 11, which matches the guide groove 10, is provided at the upper corner of the mounting base 1-2. During mold closing, the guide post 11 inserts into the guide groove 10. The tapered surface fit automatically corrects minor misalignments between the upper mold 3 and the mold base 1, ensuring mold closing accuracy. The clearance between the guide post 11 and the guide groove 10 is 0.02~0.05mm, and the taper is 1:10 to 1:20.

[0021] The detachable connection between the mold 2 and the mounting base 1-2 employs a combination of sliding guide and pin locking. Specifically, the mold 2 has downwardly extending guide bars 12 on its two opposite sidewalls, with cylindrical or conical insert rods 13 at the bottom of the guide bars 12; the inner wall of the cavity 1-3 of the mounting base 1-2 has two guide grooves 14, which are dovetail grooves that slide in conjunction with the guide bars 12, allowing the guide bars 12 to be pushed into the guide grooves 14 from above; the bottom of the guide grooves 14 has slots 15 that mate with the insert rods 13. When the mold 2 is pushed into place along the guide grooves 14, the insert rods 13 are precisely inserted into the slots 15, restricting the horizontal movement of the mold 2 along the guide groove direction. To further prevent the mold 2 from rotating or tilting under the impact of casting, a limiting hole 16 is provided at the inner bottom corner of the mounting base 1-2, and a limiting rod 17 that mates with the limiting hole 16 is provided at the bottom of the mold 2. The clearance between the limiting rod 17 and the limiting hole 16 is 0.02~0.05mm. Usually, two or four limiting rods are provided, distributed diagonally. All six degrees of freedom of the mold 2 are reliably constrained. At the same time, when the mold needs to be replaced, it can be pulled out in reverse, which is simple to operate.

[0022] The upper mold 3 also integrates a gating system. The top of the upper mold 3 has a pouring cup 6, inside which are sequentially connected a sprue 7, a slag collection pot 8, and an ingate 9. The upper part of the sprue 7 connects to the pouring cup 6, and the middle part has a slag collection pot 8. The diameter of the slag collection pot 8 is larger than that of the sprue 7, which buffers the molten iron and allows slag to float. The slag collection pot 8 has a ceramic fiber slag-blocking mesh inside, with a mesh diameter that effectively intercepts oxide inclusions in the molten iron. The lower part of the sprue 7 has an ingate 9, which corresponds to and connects to the casting cavity 4. Molten iron is poured from the pouring cup 6, slowed down by the sprue 7, passes through the slag collection pot 8 for slag settling and blocking, and finally smoothly enters the cavity 4 through the ingate 9, avoiding air entrapment and sand flushing. In addition, the upper mold 3 also has an exhaust port 26, which connects to the parting surface, to smoothly discharge the gas inside the cavity.

[0023] To improve the working environment and protect the mold, the upper part of the base 1-1 is equipped with upward-protruding slag-blocking strips 23 around its perimeter. These strips can block molten iron and scattered molding sand that may splash or overflow during pouring, preventing them from affecting production safety. The slag-blocking strips 23 have openings 24 for easy cleaning of accumulated slag. The bottom of the mold base 1 is equipped with a heat insulation plate made of ceramic fiber or mica board, effectively preventing heat transfer from the mold to the worktable and preventing thermal deformation of the worktable. The mold base 1 has several through holes 25 around its perimeter for fixing the entire mold to the casting worktable or automated production line using bolts.

[0024] The cooling mechanism is crucial for ensuring the solidification quality of ductile iron. In this embodiment, the cooling mechanism includes an inlet channel 18, a cooling channel 19, and a return port 20. The inlet channel 18 is located inside the base 1-1, with one end passing through the side wall of the base 1-1 and connected to an external coolant source, such as water or special cooling oil, and the other end connected to the bottom inlet of the cooling channel 19. The cooling channel 19 is spirally arranged inside the mounting base 1-2 and surrounds the mold 2. The spiral cooling channel maximizes the heat exchange area between the coolant and the mold, while ensuring uniform circumferential temperature of the mold 2. The cooling channel 19 is equipped with a turbulent flow stage 28 to forcibly disrupt the liquid flowing into the spiral cooling channel 19, transforming the laminar coolant into a turbulent state, significantly increasing the contact heat exchange area between the coolant and the inner wall of the channel, and enhancing the heat exchange efficiency between the mold base 1, the mold 2, and the coolant. The upper outlet of the cooling channel 19 is connected to the return port 20, which passes through the side wall of the mounting base 1-2 to discharge the cooled liquid after heat absorption. Depending on the location of the hot spot in the casting, the pitch of the spiral can be set to be unequal, with the pitch decreasing in the corresponding area of ​​the hot spot to enhance local cooling.

[0025] The ejection mechanism specifically includes a cylinder 21 and a top plate 5. A storage cavity 22 is machined inside the base 1-1, and the cylinder 21 is installed within this cavity 22. The piston rod of the cylinder 21 extends upward and is fixedly connected to the top plate 5; the upper surface of the top plate 5 corresponds to the bottom surface of the casting cavity 4. The top plate 5 is preferably made of H13 hot work die steel, with a quenching hardness of HRC50~54 and surface nitriding treatment to withstand demolding temperatures of 500~600℃. To prevent high-temperature molten iron from flowing into or seeping into the storage cavity 22 inside the base 1-1 during pouring, the gap between the top plate 5 and the inner wall of the storage cavity 22 is controlled between 0.1~0.2mm, ensuring smooth up-and-down movement of the top plate 5 while utilizing the surface tension of the molten iron to prevent easy seepage. The air inlet and outlet pipes of the cylinder 21 pass through the side wall of the base 1-1 and are connected to an external compressed air source and control valve. After the casting solidifies, cylinder 21 is vented, the piston rod rises, pushing the top plate 5 upwards, and smoothly ejecting the casting from cavity 4. After ejection, cylinder 21 is vented in the reverse direction, and the top plate 5 returns to its original position.

[0026] This invention is applicable to ductile iron castings with flat top and bottom surfaces, including but not limited to: plate castings, such as machine tool worktables, platforms, and base plates; gasket castings, such as flange gaskets and bearing end caps; and base castings, such as motor bases and equipment mounting seats. For these castings, since both the top and bottom surfaces are flat, a planar upper mold structure is sufficient to meet the forming requirements, eliminating the need for complex cavity machining. Simultaneously, the top plate directly ejects the bottom surface of the casting, leaving no ejector pin marks on the casting surface, thus ensuring the appearance quality and dimensional accuracy of the casting. The maximum size of the casting suitable for this mold depends on the machining capabilities of the mold base 1 and mold 2, as well as the position of the ingate 9. The machining capabilities of the mold base 1 and mold 2 determine the maximum possible cavity contour range; the position of the ingate 9 directly affects the flow path of molten iron into the cavity and the filling effect.

[0027] In use, first, select the corresponding mold 2 according to the shape of the casting to be produced, and push it into the cavity 1-3 of the mounting base 1-2 along the guide groove 14, so that the insert rod 13 is inserted into the slot 15 and the limiting rod 17 is inserted into the limiting hole 16 to ensure accurate positioning of the mold 2; then, hoist the upper mold 3 above the mold base 1, and complete the mold closing by guiding the guide column 11 and the guide groove 10, and use bolt pressure plates to fix the upper mold 3 to the mold base 1; start the cooling system to circulate the coolant in the spiral channel; then pour the qualified ductile iron into the pouring cup 6, and the molten iron fills the cavity through the gating system; after holding the pressure and cooling for a certain period of time, after the casting is completely solidified, open the mold, start the cylinder 21, push the top plate 5 upward, and the upper surface of the top plate 5 directly contacts the bottom surface of the casting, and smoothly eject the casting from the cavity 4. After removing the casting, check that there are no ejector rod marks on the bottom surface of the casting, the surface is flat, and clean the cavity. When it is necessary to change the product type, simply loosen the upper mold 3, remove the prototype mold 2, replace it with the new mold 2, and then close the mold again.

[0028] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A casting mold for ductile iron, characterized in that: It includes: The mold base (1), the mold (2), the upper mold (3), and the cooling mechanism are provided. The mold base (1) is detachably connected to the mold (2). The mold (2) has a casting cavity (4) that extends through its thickness. The cooling mechanism is provided inside the mold base (1) located around the mold (2). The upper part of the mold base (1) is detachably connected to the upper mold (3). The bottom of the upper mold (3) is a flat surface. The mold base (1) includes a base (1-1) and a mounting seat (1-2) located on the upper part of the base (1-1); the upper part of the mounting seat (1-2) is recessed downward to form a cavity (1-3) adapted to the mold (2), and the mold (2) is detachably connected inside the cavity (1-3); the base (1-1) is provided with an ejection mechanism inside, and the top plate (5) of the ejection mechanism passes through the upper part of the base (1-1) and corresponds to the casting cavity (4), and is used to eject the solidified casting from the casting cavity (4); The mold base (1) is provided with a heat insulation layer (27) inside, which is located outside the cooling mechanism and below the ejection mechanism.

2. The casting mold for ductile iron according to claim 1, characterized in that: The top of the upper mold (3) is provided with a pouring cup (6), and the interior is provided with a gating channel (7), a slag collection bag (8) and an inner gate (9) connected in sequence. The upper part of the gating channel (7) is connected to the pouring cup (6), and the middle part is provided with the slag collection bag (8). The diameter of the slag collection bag (8) is larger than the diameter of the gating channel (7), and the slag collection bag (8) is provided with a slag-blocking mesh inside. The lower part of the gating channel (7) is provided with the inner gate (9), and the inner gate (9) is connected to the casting cavity (4).

3. The casting mold for ductile iron according to claim 1, characterized in that: The bottom corner of the upper mold (3) is recessed upward to form a guide groove (10), and the guide groove (10) is a frustum shape that is narrow at the top and wide at the bottom; the upper corner of the mounting base (1-2) is provided with a guide post (11) that is compatible with the guide groove (10).

4. The casting mold for ductile iron according to claim 1, characterized in that: The mold (2) has downwardly extending guide bars (12) on its two opposite side walls, and the bottom of the guide bars (12) has a plug (13). The inner wall of the mounting base (1-2) is provided with two guide grooves (14), and the guide grooves (14) are dovetail grooves. The guide grooves (14) and the guide bars (12) slide in fit. The bottom of the guide grooves (14) is provided with slots (15) that are compatible with the plug rods (13).

5. The casting mold for ductile iron according to claim 4, characterized in that: The mounting base (1-2) has a limiting hole (16) at the inner bottom corner, and the bottom of the mold (2) has a limiting rod (17) that matches the limiting hole (16).

6. The casting mold for ductile iron according to claim 1, characterized in that: The cooling mechanism includes an inlet channel (18), a cooling channel (19), and a return port (20). The inlet channel (18) is located inside the base (1-1), with one end passing through the side wall of the base (1-1) and the other end connected to the bottom inlet of the cooling channel (19). The cooling channel (19) is spirally arranged inside the mounting base (1-2), and a small turbulence flow platform (28) is provided inside it. The upper outlet is connected to the return port (20), which passes through the side wall of the mounting base (1-2).

7. The casting mold for ductile iron according to claim 1, characterized in that: The ejection mechanism includes a cylinder (21) and a top plate (5). The cylinder (21) is installed in the storage cavity (22) inside the base (1-1), and its piston rod extends upward and is fixedly connected to the top plate (5). The air inlet and outlet pipes of the cylinder (21) pass through the side wall of the base (1-1).

8. The casting mold for ductile iron according to claim 1, characterized in that: The upper part of the base (1-1) is provided with upward protruding slag-blocking strips (23), and the slag-blocking strips (23) are provided with openings (24).

9. A casting mold for ductile iron according to claim 1, characterized in that: The bottom of the mold base (1) is provided with a heat insulation plate and several through holes (25) around it for fixing the mold base (1) in place.

10. A casting mold for ductile iron according to claim 1, characterized in that: The base (1-1) and the mounting base (1-2) are integrally formed.

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